1. Field of the Invention
The present invention relates to an intake control apparatus controlling an amount of air flowing toward an engine, and more particularly to a tandem valve type throttle body for a two-wheeled vehicle provided with a main throttle valve for opening and closing an intake passage provided through in an inner portion of a throttle body in accordance with an accelerator grip operation by a driver, and a sub throttle valve driven and operated by an electric motor driven in correspondence to an operating state of the engine for opening and closing the intake passage at an upstream side from the main throttle valve, within the intake passage.
2. Description of the Conventional Art
Japanese Unexamined Patent Publication No. 2005-90471 discloses a conventional tandem valve type throttle body for a two-wheeled vehicle having a main throttle valve operated by a driver and a sub throttle valve operated by an electric motor which are arranged within an intake passage provided within a throttle body, opening the sub throttle valve by driving the electric motor at a time when the main throttle valve is fully closed, and forcibly opening the main throttle valve toward a first idling opening degree on the basis of an opening motion of the sub throttle valve independently from an operation of an accelerator grip.
According to the structure in the Japanese Unexamined Patent Publication No. 2005-90471 mentioned above, the main throttle valve attached to a main throttle shaft is arranged in an intake passage provided so as to pass through the throttle body, a throttle drum is attached to one end of the main throttle shaft, and the throttle drum is connected to an accelerator grip operated by a driver with a valve opening wire and a valve closing wire.
Further, the sub throttle valve attached to a sub throttle shaft is arranged in the intake passage at an upstream side from the main throttle valve, and the sub throttle valve is operated by an electric motor driven in correspondence to an operating state of the engine.
In other words, the throttle drum is rotated forward and backward via the valve opening wire and the valve closing wire on the basis of the operation of the accelerator grip by the driver, whereby the main throttle valve opens and closes the intake passage. Further, the sub throttle shaft is rotated forward and backward by the electric motor, whereby the sub throttle valve opens and closes the intake passage.
On the other hand, a cam lever having a cam surface is attached to one end of the sub throttle shaft, a driven lever having a roller is attached to one end of the main throttle shaft, and the roller is arranged so as to face to the cam surface of the cam lever. In accordance with the structure mentioned above, the main throttle valve mechanically controls so as to open and close the intake passage by an accelerator grip operated by the driver, and the sub throttle valve electrically controls so as to open and close the intake passage by the electric motor driven in correspondence to the operating state of the engine. Further, when the sub throttle valve is fully opened by the electric motor, the cam surface of the cam lever rotates the driven lever via the roller, whereby the main throttle valve opens the intake passage at a fixed opening degree toward the first idling opening degree independently from the operation of the accelerator grip.